1. Field of the Invention
The present invention relates to a work vehicle using a single operation lever for effecting both speed change operations and a parking brake operation.
2. Description of the Related Art
Conventionally, as an example of such work vehicle as described above, there is known e.g. a work vehicle disclosed in Japanese Patent No. 3979706 (paragraphs [0007] through [0019]; paragraphs [0033] through [0038], FIGS. 7 through 17). More particularly, this work vehicle includes a transmission mechanism for transmitting a rotational drive power from an engine to a traveling device, a speed changer device (referred to as a “main speed changer device” in the document) disposed in the transmission mechanism and capable of changing the vehicle speed through speed changing of the rotational drive power, a parking brake device capable of restricting the operation of the transmission mechanism (referred to as a “parking lock device” in the above document), and an operation lever manually pivotably operable and capable of braking the speed changing operations of the speed changer device and the braking operation of the parking brake device.
This tractor includes a single operation shaft coupled to an operation lever so as to act in response to an operation of the operation lever and operably coupling the operation lever, the speed changer device and the parking brake device to each other, and a locking mechanism capable of maintaining the parking brake device under its condition of restricting the operation of the transmission mechanism (in the document, “ a lever guide” and “an engaging portion” which is the lower end of the operation lever).
The technique disclosed in Japanese Patent No. 3979706 adopts the arrangement of the single operation shaft operably coupling the operation lever, the speed changer device and the parking brake device to each other, such that with operations of the single operation lever, both the speed changing operations and the parking brake operation are effected.
Further, in the technique disclosed in Japanese Patent No. 3979706, a neutral path is extended beyond the area including speed changing paths and there is provided a brake operation path that extends straight from the terminal end of this neutral path along the direction intersecting this neutral path (the direction parallel with the speed changing paths). In operation, when the operation lever is operated along this brake operation path, the operation member is pivoted, thereby to pivot the parking brake mechanism to effect a parking brake operation.
Further, beyond the terminal end of the brake path, there is provided a locking path for actuating the locking mechanism and there is provided an arrangement that inhibits an operation of the operation lever from the locking path toward the neutral path (braking path), thus preventing the operation lever from being disengaged from the braking path to result in inadvertent release of the parking brake.